Method and apparatus for mixing and rendering plastic pulverulent materials



C. E. OSBORNE Nov. 1s, l1941.

METHOD AND APPARATUS FOR MIXING AND RENDERING PLASTIC PULVERULENTMATERIALS Filed Sept. 23, 1944 Patented Nov. 18, 1947 METHOD ANDAPPARATUS FOR MIXING AND RENDERING PLASTIC PULVERULENT MATERIALS ChesterE. Osborne, Rahway, N. J., assgnor to Paul 0. Abbe, Inc., Little Falls,N. J., a corporation of New Jersey Application September 23, 1944,Serial No. 555,502 16 claims. (o1. 11i-'12) This invention relates to animprovement in apparatus, and method of incorporating, or renderingplastic, with suitable solvents or bonds, granular or pulverulentmaterials, which are used as aggregates for making paints, lacquers,resins, rubber, smokeless powder, some food products. and various typesyof solidified plastic products, and is also useful for intimatelyintermixing and forming pulverulent plastic and electrolytic compoundsor ingredients.

This application is a continuation in part of my co-pending applicationSerialNo. 242,200, filed November 25, 1938, claims 1 to 16 herein beingcopies of allowed claims in said co-pending application.

The present device has, as a principal feature, the provision of ahousing in which is Ylocated a constantly rotating mixing and reducingmeans whereby, by a continuous, operation thereof, granular orpulverulent materials'may be fed, mixed, treated, formed and dischargedtherefrom, in a continuous manner.

A further, specific feature is in the provision of a rotary means in acylindrical chamber, comprising driven feed and mixing parts orshaftswhich may be driven at similar or' dissimilar speeds.

A further feature is the provision, in a mixing chamber, of meanswhereby said parts may comprise alined feed and mixing worms the ends ofwhich may, if desired, be spaced apart and operatively held clear ofeach other thus providing a mixing chamber therebetween. In someinstances the ends of the worms may not require the provision of amixing chamber, and the worms working diameters may ,then besubstantially continuous.

In some instances the mixing shaft may be plain.

A further feature of advantage is that the Worm structures are soconstructed that they may be rotated in the same or opposite directionswith one another. The worms may also be provided with threads thereon oflike or opposite pitch or lead, so that during the operation thereof,they may feed material toward each other, to cause an intimate mixing,shearing, and compressive kneading of the material being treated.

In other forms the worm may be made of the same pitch, but of differentdiameters, but may be rotated in opposite directions of rotation, thusto obtain counter-acting mixing operations, or counter-flow of thematerial being treated.

In the operation of the herein apparatus, the respective diameters ofthe worms, the respective pitches of the threads and the speeds anddirections of rotation of the respective worms may be altered, as may berequired by materials being treated.

During the mixing and kneading operation, as will be more readilyunderstood as described later, the materials being treated may beintermixed with a suiiicient amount of a solvent or suitable liquidbond, to cause the material to become plastic to any desired degree ofviscosity and 4to finally be discharged from the discharge end of theapparatus in a completely plastic, molded condition, in any varyingdegree of viscosity desired.

A further advantage in the present construction, is in the provision ofa foraminous discharge or extrusion plate which is `located at thedischarge end of the apparatus, the perforations of the said plate beingof any desired form-dimension or contour, and from which apertures thethoroughly: mixed, plastic material is discharged, continuously, in thedesired cross Sectional contour and dimension.

Afurther advantage of the present construction, as will hereinafter beexplained more inV detail, is in the provision and means in associationwith the extrusion plate or die, whereby aggregates of smokeless powder,after being thoroughly mixed and made plastic therein, may be extrudedthrough the said plate, and, during such extrusion the dischargedmaterial is provided with the usual central perforations, so that, whenthe apparatus is used in the manufacture of smokeless powder, theoperation is continuous. After the extrusion process, the smokelesspowder may be dried and broken into the desired lengths involved. ThisAparticular, improved method of making smokeless powder eliminatesundesired hazards, and eliminates extra handling and operations, whichare current practice.

The foregoing, and other features of advantage will be apprehended asthe herein description proceeds, and it will be obvious thatmodifications may be 4madein the structure herein, without departingfrom 'the spirit hereof or the scope `of theappended claims.

milling and feeding worms from the apparatus for inspection, repair,replacement or substitution, and cleaning:

Figs, 3 and 4 are front and side views of the extrusion plate;

Fig. 5 is a sectional View taken on line 5-5, Fig. 1, looking in thedirection of the arrows;

Fig. 6 is a sectional view, taken on the line 5 6, Fig. 1i, looking.'in' ythe direction. oftheiarf rows; f 5 l Fig, 7 is an enlarged,fragmentary sectional View of the extrusion plate showing Certain details of structure; y

Fig. 8 is a fragmentary enlarged viewl side elevation of the inside faceof the extruding plate when assembled for the manufacture of smokelesspowder; i

Fig. 9 is an enlarged end View of'a' smokeless powder grain made by thepresent apparatus;

Fig. 10 is a side elevation. showing a. modified'.

form of mixing and reducing shaft, the shaf being without any worm andplain.

InvFigs. 1 and 5, there is shown the chambered structure, inther presentinstance, comprising an innerv solid' walled mixingy cylinder I'II.,which is provided with integral endrv flanges: I5.-I.5,. and is Withoutany joints within its interiori.. The mixing cylinder Iltis rigidlymounted within an outer split casing, generally. denoted by If, Fig. I,and as` seen in Figs.. 2 and 5.1,. the split. casing. is constructed.ofv upperV and lower 'outer sections 2 and 21 and upper and lower innersections 3f and 3:. Both the inner and' outerI sections are/pref.'-erably cylindrical' andv are.integrally connected to cylindrical' en-d.ilanges '5-51,l the. lower flange sections; merging' intof clamping?`side.- flanges I5-I 5, Figs. 4 and 5.

The lowerr outer housing secton, iFig... I, .has its end flange portions5 5.- integrally connected to supporting base .extensions 8:-8g thesein. turn being provided with. angular'toot extensions4 9:-9, which areeach provided with. gib extensions: I,

Fig. 5,. said. gibs I' being: slidafb'lyr.engagedy in outer housingsection 2 and the inner faces: of

the. base extensions 8 8 and;&.-9=rigidifying the housinglconstructiona-nd its attachment to base fra-me B.. V"lhe base extensions8-8 -9-9' are removably locked by locking screws,.studs.or bolts Inassembling the mixing cylinder Iflrinr its operative relation it isclamped in its operativepo.- sition by flange clamping. screws I'I-Iwhich bind` the Youter and inner housing-structure.. t-o mixingcylinder. Ill.r

The outer housing; I isprovidediwith a. steam chamber IlY whichlsurrounds theA inner mix-ing cylinder` I-Ll:I sothat,A when desired,steam` or: hot or cold water mayv be; introduced atv theinlet port orduct 'I-, and discharged from: discharge, or outlet duct t',l undervalve'y and pressure; control means notshown. but understood.. Y f

The apparatus is. providedwith.amaterial holding and feeding hopper. H;the. lower; end; being provided with a bored hub: pflltion. Zilrthefbore of which rotatably supports theoutenend of a feeding worm 2in. .Thehopper. is;v provideidgorr its face,radjacent. the flange I l5.- ofthe-,mixing cylin.- der Ill, with an attaching-harige.119;,v which isfirmlyk held. tothe flange l5 of` said cylinder'l It, by', afseries of.headedbolts,4 one of which 22,v is showninFig. 1.. A i f The outer end23 of the worm.V T isr provided With an integral thrust shoulder-523;whi'ch is in operativelrearwa-rd thrustotthe worm 2t is taken up by theshoulder 30 of the bearing, generally denotedby D.

TheloearingI 2l?.` is provided with an inner, xed bearinglir-ier 29},.which is rotatably supported the integra-I, rear shaft extension 36 ofthe feed worm 'I'. An oil aperturer O is provided for lubric-:ati'ngythe sha-ft 35 and its bearing.

means, such as a; gear 38, which is aflixed to said shaft., endiby a;suitable keying means, such as a key pin 3I, which passes through thegear hub Ilflliand the shaft 36.

The bearing 28 is provided withintegral support' legs: 3f.I'-3&, whichinv turn areprovidedy with ai.. common. slide; base 35i; this. irI turnbeing 'provided-1 on. itsV under face with: an extending gib I: 0'..whichiits intol andrslidesi'n thev gib-way GLG, im baseBg. as. describedfory slideibases` te-3f. The bearing supportcomprising: saidV bearing38:, legs Sir-3d and slide. base 35g, generally denoted'. by D; Fig.I1,. andv the. worrnfZ If and drive means. carried thereby areiremovablyrheldv infoperative position as illustrated inzFigr 1 b'yfathreadiedilockbolt. 33..

It being.' desirable: at: times, to'1 slide. the feeder worm and. itsappurtenanti support means. away from the mixing: cyl-indem. this; isaccomplished by removing the bolt 33, and sliding thefentireassemblyrearwardly orr. base: By as. shown in. Fig. 2.; This permits of4inspection, repair orireplacelment.otsthefworm-'Itasdesired;

practical operation, the. outside; diameter" of the threads of worm: 'Iis such; as to rotatively ft in; the bores of*v the mixing; cylinderI4", thereby to insure positive feed=ofthez material;A suppliedV by:the. hopper H, to ther-mixing. chamber and from thence through the".apparatus and through: .the extrusion discharge plate-43e..

.ltxthel oppositeend= of4 the apparatus, azs'ec'-r extruding dieplate;la are iirstt removed, as shown Y nEig. 2, and some: oftheaistruoturalfdetails are indicated. in: their 'structural' similaritybyI kthe use or likeindicesVY for indicating: like.` parts.,l Thebearing C, andL itsy appurtenant apparatus; is

Y pin. 31., whiche passesthroughxthe gear is of smal-1er diameteratnanfeeding worm. T,

andmavyY have its.; thre'axls` in. the. same direction as,yorfinxafrevcrse helix. toqthatofsthe wormsf.

'It may alsobe: of. unlike. pitch; orfjleadg: sorthat during. rotation.off both wormsgyinedire'ctiorr ofv Y rotation of. each: may:beopposedpto eachf other, and thecompressive action-'on 'the .materia-1'being treated by thedifferentlyA feedingwormsztending Vto,'amaigamatetliemateriali intoi a1:".pl'a'stic condition quickly. y Y L jllihefwormI T' may be.oonstructediandfrotatedfto On the rear` extendingend of shaft 36 is located a driven feed the material engaged by theworm T toward the worm T or more or less slowly toward the die plate 43.

Instead of providing the worm T', the shaft 56 may be provided with aplain mixingportion T as in Fig. 10, as it has been found that theapparatus is surprisingly eiiicient with the plain mixing portion T. Inany case, the action of the shafts 35 and 55 is such that the materialpasses slowly through the mixing chamber 42 and is there a long timereduced and mixed under very high pressure.

The invention is not limited to the relative directions of the threadsof the worms T and T. It is obvious that if the threads are in the samedirection, as shown, that the rotation must be in opposite directions tocause opposed feeding. To give opposed feeding while rotating in thesame direction would require that the threads should have oppositepitch. Thus to give opposed feeding, it is possible to have the threadsof the same or opposite pitch depending upon whether the direction ofrotation are in opposite or the same directions.

The part of the shaft 55 within the cylinder may be relatively muchlonger or not as long as shown; and for some purposes the shaft may beplain or only part is provided with worm threads, or all of the threadsneed not be in the same direction; and in extruding some shapes ofsmokeless powder, rods or tubes, it is desired that the pressure at thedie be not too much reduced by the counter threads T.

The active portions of the worm T or plain portion T may be aboutfour'times its diameter or less or much more if conditions require; andtheir diameter may be nearly as large as that of the chamber 42.

The action of the shafts 36 and 56 tends to expel all air from thematerial and to force the material, as it travels through the mixingcylinder, into the mixing chamber or space I8, Fig. 1, which is formedby and between the spaced, adjacent ends of the shafts. The ends of theshafts may each be provided with traverse grooves I9, which are cut intothe faces of said ends. One or both of these may be omitted if desired.While only one groove is shown traversing said ends, a plurality ofgrooves i9 may be cut therein.

During the travel of the material through the mixing cylinder, it is fedin constant volume by said feed worm T, and is gradually forced intosaid mixing chambel` I 8, and then is gradually forced past said mixingchamber and into the thread of the mixing worm T or the plain portionT". If the worm T counterfeeds, the material is forcibly reversed in itsflow. The material is thoroughly mixed and gradually lls the clearance42 around the mixing shaft, and the piled up excessive material in theclearance is gradually forced toward the discharge end of the apparatusand during such flow is constantly sheared, reduced and mixed by themixing shaft 55.

When the material nally reaches the extrusion discharge recess or spaceS', it is forcibly extruded through the apertures Il-41, of theextrusion plate 43 and the discharged, thoroughly mixed and plasticmaterial is removed for further treatment, such as drying, breaking up,etc.

During the constant feeding of the dry, pulverulent material into thehopper I-I, there is introduced suiicient liquid solvent, liquid bond,water or similar plasticizing ingredients in sufficient quantity toreduce the dry material to the desired viscosity, according to its lnalutilization. This viscosity varies in accordance to the use to which thefinally discharged product, such as paints, lacquers, resins and thelike, as hereinbefore noted. These products are functionally different,for'diiferent uses. Some end products of the herein apparatus may be ofacetate or phenolic bases and are afterwards used for molding objects ofdifferent function and use, and these varying aggregates require thatthe final product be of varying viscosities, heavy or light.

The diameter of the shaft 56 is smaller than the diameter of the mixingworm T (Fig. 1) or' portion T (Fig. 10) thereon, the larger diameterpart terminating near the outside face of the flange I5 of the mixingcylinder I4. The extrusion plate 43 is of disc formation and isdiametrically split at 50, Figs. 3 and 4 to permit it to be fitted overthe shaft 56 by its split bore 49. This construction affords means toremove the plate for repair or replacement, or in some instances,replacement by a plate having larger or smaller extrusion apertures, orhaving apertures of different cross-sectional contours.l

When placed in operative position on the shaft 56, the extrusion plate43, having a recessed face 48 to provide the end or discharge clearancerecess 5', is then locked in firm position by a plate locking ring 44,which has a bevel-ended ange 4B, which engages the perimeter of theplate 43, the flanged construction providing an open bore 51, Fig. 1,and the said plate locking ring 44 is rigidly and removably held to theflange I5 of the mixing chamber cylinder I4 by suitable headed bolts 45.By this construction, the extrusion plate 43 is firmly and removablyheld in a leak proof assembly with the flange i5 of the mixingv chamberI4.

If during operation the worm T moves material away from the dischargeend and is, therefore, free of tendency to feed the engaged and rubbedmaterial in a direction toward the discharge end. This avoids hasteningthe material through the apparatus by the worm T', whereby the materialmay be longer subjected to the rubbing and reduction action while freeof such pressure as would cause packing at the discharge end. As theworms T and T are separately driven, the amount Iof reducing action ofthe worm T relative to the speed of material may be convenientlyadjusted.

The present apparatus is particularly fitted to manufacture smokelesspowder, and to this end an .extruding plate or die 43, shown in enlargedfragment and cross section, in Fig. 7 and in fragmentary, enlargedelevation in Fig. 8. The plate is made in two split halves, as describedfor Figs. 3 and 4, and has a recessed face 48. The plate is providedwith extrusion apertures 47, Figs. 7 and 8, into which extend aplurality of wires 52. These wires are rigidly mounted at one end in anoffset bracket 5I, the offset portion being mounted out of contact withthe face of recess 48, and is thereby spaced therefrom. The bracket 5Ihas two opposed and angled foot portions, which rest on the face ofrecess 48, and these are held thereto by screws a-a, Fig. 8. Thus theextruding apertures are provided with spaced apart prongs, which, whenthe smokeless powder batch is extruded therethrough, causes a pluralityof more or less symmetrically located holes to be continuously formed inthe extruded powder forming rods, during the process of extrusion. Therods may be afterwards dried and cut, or broken into the desiredproportioned grains.

Y Baring. the making of the smokeless powder,l the various ingredients.are. entered, continuously, into the. hopper with. sufficient liquidi toamal` gamatethemass' to the desiredstiiness, and. upon. reaching thedischarge end. of the herein appa-y ratus', the moving materialsurrounds the bracket 511 andl enters the extruding apertures: 41,. andtheextruded material emerges continuously from the: apertures` 4i, withaseries of continuous, parallel apertures 55 within the body 54' thereofrthese1 being formed therein, automatically bythe.- actief extrusion, andas illustrated in Fig. 9, which is a side view of a smokeless powdergrain, enlarged.

Tubular bodies of various materials, may also be made in the foregoingapparatus, by the pro-- vision of' suitable extruding die plates'-- Itis amongst` the possibilities of the present apparatus tomake macaroni,with the provision of a proper extruding die, and the use of Semolinawheat flour', admixed with water and both thoroughly' admixed by andextruded from the herein disclosed apparatus.

Any suitable form of drive means for the shafts 36 and 56 may beutilized, and such drivev may consist of a separate electric motorgeared to each gearv 38, or an individual electrically driven chaindrive or a pulley counter drive.

In the operation of thel apparatus herein, some materials may requiretemperature treatment, either hot or cold, and to thisr endthe housingl', as illustrated in Figs. 1 and 5, is provided' with a chamber 4, and,as required, steam, hot or cold Water may be passed intothe inletportl1, and out ofthe discharge port 6, thus" to transfer temperaturesdesired to the material in cylinder i4, during operation on the materialbeing treated. In this event, the material may require no liquid bond orsolvent, applied heat being sunicien't for .the purpose of ren-deringthe material plastic.

The present apparatus is particularly adapted for treating unvulcanizedrubber for incorporating tempering ingredients therein for increasingthe temper of the rubber for vehicleV tirev treads and the like. By thepresent4 method and appa- Y ratus, a batch of unvu'l'canized rubber'maybe fed into hopper H, together with predetermined quantitles of'carbon black', or other known tempering materials, and thus impregnatovthe batch. with a greater amountY of tempering. material than heretoforepossible by any othenknown method, and'v thus the wearing qualities andtoughness" of the' rubber, forl tires and other uses, is greatlyenhanced.

The grinding', mixing and reducing action of' the several apparatusmethods herein isi surprisingly more efficient than was thoughtpossible, producing a colloidal action equivalent to a completedispersion of the particles during the mixing. For instance, carbonblackwith a little sollvent may'in the apparatusbe. reduced' to aplastic of colloidal consistency which will' when` thinned out remain insuspension without settling and which under the microscope willV showparticles of carbon of, colloidal size..

Having thus'described the invention, what. is ciaimed is:

A material Ymixing machine comprising a 8 at. the opposite end thereof,a threaded mixing wormoperatively mounted in. said cylinder-for rotationtherein and through said die, for mixing. the material fed thereto fromsaid rstworm, the; threads of said wormsbeing.' of opposite pitch andmeans for rotating said worms.

2.. A. material. mixing machine: comprising arr open. ended mixingcylinder, a temperature controlling. jacketr surrounding said cylinder,a base' means for mounting. said cylinder and jacket in operativeposition thereon a material` feeding hopper connected to saidcylinder-,1a threaded feeding Worm operatively mounted for rotation insaid cylinder'at one end thereof, to feed material from saidv hopperinto said cylinden an extruson die connected to said. cylinder vat theopposite end thereof, a threaded' mixing worm operatively mounted forrotation in said cylinder and said die for' mixing the material fedthereto from said nrst worm, the threads of said. worm being of`opposite pitch and means for operating said` worms..

3. A pulverul'ent. material mixing machine com'- prising an open endedmixing cylinder having inlet and discharge.- ends, a base, a gib-way onsaid base for iixedly mounting said cylinderl i-n operative positionthereon, a material feeding hopper mounted on the inlet end of saidcylinder, a. threaded, rotatable feeding worm iixedl-y, releasablyl andslidably mounted in said cylinder at thev inlet end to feed materialfrom said hopper into said cylinder, anextrusion die connectedy tosaidcylinder at the discharge end thereof, a threaded mixing wormrotatably mounted through said die and into the Vdischarge end-'of saidcylinder for mixing the materialv fed thereto from said: first worm, thethreads of said worms being of opposite pitch, means Yfor operating saidWorms anda temperature conducting housing `enclosing said cylinder;

4r. A pufl-verul'ent material mixing machinecompri/sing an open endedmixing cylinder, a base, means for fixedly mounting; said' cylinder inopera'- tive positionl thereon, a material feeding hopper discharginginto one end of the cylinder, alined threaded feed-ing and mixing Awormsrotatively mounted in said cylinder at opposite ends thereof tolinearly'ieed material from said hopper by said feeding worm toA saidmixing worm, an extrusion diel connected to said cylinder at the .mixingworm end thereof, the mixing worm being rotatively mounted through saiddie, the threads of said' wormsvv being of opposite pitch, theadjacent.' endsY thereof being spaced apart to provide a mixingchamber'therebetween, the faces. ofthe adjacent Worm endshavingmaterial` mixing means thereon, and means for operating saidworms, both worms being between the hopper and die.

5. The method of. mixingy and rendering plastic a pulverulent orgranular material consisting of introducing a liquid bond or solventinto the ma.-

mixed material: against the' fed material and't'h'en extruding themixed" material.

6,. In mixing, a method which co-mpri'sesprovidi-ng a tubular space;forcing material under high pressure into said space substantially atone end, thereby to compress the'material'in said space; allowing escapeof the materialsubstan'- tially at' the other end of the space at highpressure and in small amount, thereby to maintain the material at highpressure in the space and A. cause portions of the material to passslowly along direction said pressures being high enough to effectivelyreduce the material. i u

7. In mixing, an apparatus which comprises means providing a tubularspace; means for forcing material under high pressure into said spacesubstantially at one end, thereby to compress the material in saidspace; means for allowing escape of the material at the other end of thespace at said space in a direction from said first named end to saidother end; and means for engaging limited spaced quantities of saidmaterial disposed along faces transverse to the axis of said space andspaced along the inner surface of said tubular space and moving saidquantities counter to said first direction, thereby to cause saidquantities to be engaged, reduced and mixed by engagement with saidportions moving in said rst direction.

8. An apparatus comprising means providing a tubular space having adischarge end; a closely tting rotary worm in said space spaced from thedischarge end for forcing material under pressure into the end portionthereof between said worm and discharge end, thereby to compress thematerial in said portion; discharge means for a1- lowing discharge ofthe material at said discharge end in small amount, thereby to maintainraised the pressure of the material in said portion and cause thematerial to pass slowly along said portion to said discharge end; and aseparate rotary worm smaller in diameter than said space, and disposedin said portion for engaging said material; means for rotating saidseparate worm in a direction to move some of said material in adirection away from the discharge end, to further increase the pressureof the material and cause said material to be engaged under highpressure with a separate worm and to be reduced and engaged under highpressure with and mixed with said portions moving toward the dischargeend.

9. In mixing, a method which comprises forcing material under highpressure into one end of, and along, an elongated laterally closedspace, thereby to compress the material in said space; allowing escapeof the material at the other end of the space substantially at highpressure and in small amount, thereby to maintain the material at highpressure in the space and cause portions of the vmaterial to pass slowlynear and along the outer face of said space in a direction from said rstnamed end to said other end; and forcing limited spaced quantities ofsaid material to counterfeed under high pressure in a direction oppositeto said rst direction and in contact with said portions, thereby tocause said quantities to be engaged, reduced and mixed by high-pressureengagement with said portions moving in said first direction.

10. A method which comprises forcing material under high pressure into atubular space substantially at one end thereof to compress the materialin all parts of lsaid space; allowing escape of the materialsubstantially at the other end of the space at Vhigh pressure and insmall amount, thereby-to maintain the material at high pressure in allparts of the space and cause portions of the material to pass slowlyalong the outer face of said space in a direction from said first Anamedend to said other end; and engaging limited spaced quantities of saidmaterial spaced along the inner surface of said tubular space and movingsaid quantities counter to said first direction, said pressure beinghigh enough to cause said quantities to be engaged, effectively reducedand mixed by engagement with said portions moving in said rst direction.

11. An apparatus which comprises means'providing an elongatedV laterallyclosed space; means forV forcing material under high pressure intosaidspace near one end of said space; thereby to compress thematerial-inand force it along said space; means for allowing -escape of thematerial .substantially at thev other end of the space at high pressureand in small amount, thereby to maintain the material at high pressurein the space and cause portions of the material to pass slowly alongsaid space in a direction from said first named end to said other end;means for counterfeeding limited quantities of said material under highpressure in a direction opposite to said first direction and in Contactwith said portions, thereby to cause said quantities and portions to beinterengaged and to be reduced and mixed by high pressure engagement assaid portions move in said first direction.

12. In mixing and reducing apparatus, the combination of structure meansproviding an elongated space having an inlet end and a long dischargeend portion having a discharge outlet; forcing means for forcingmaterial under high pressure from the inlet end into the discharge endportion; and a rotary shaft disposed longituf dinally in said portion,for engaging said mate- 14. In mixing and reducing apparatus, the com-`bination of structure means providing an elongated space having an inletend and a long cylindrical discharge end portion having a dischargeoutlet; means including a rotary worm in said space for forcing materialunder high pressure from the inlet end into the discharge end portion;and a rotary shaft slightly smaller in diameter than said portiondisposed in said portion, for engaging said material and cooperatingwith said structure means to form an elongated chamber of annularcross-section; drive means for rotating said shaft and worm; theeffective cross section of said chamber at all parts thereof being manytimes greater than the effective crosssection of said outlet, therebyallowing discharge of the material at said discharge end only in

